It is believed that the pertinent state-of-the-art is represented by: U.S. Pat. Nos. 2,375,190, 2,587,316, 4,377,271 and 2,256,513; U.S. patent application Ser. Nos. 2007295677, 2003057343 and 2005012016; GB patent application Ser. No. 872982; German patent application Ser. No. 102007033687; European patent application Ser. No. EP2203314 as well as by international patent applications having publication No. 9813215 and 2007069842.